Maybe it's just the paranoid side in me, but I'm curious to know if, by hitting the back button and being confronted with a "Resubmit Form?" prompt, then saying yes would result in an adjacent post being deleted, or if it would simply send a command to delete that same item, which would then see is already gone.

Anyone?

It will just request exactly the same action(s) as the form did when you first submitted it.